Last year when I attended JSConf I had some ideas about the importance of Javascript. I was concerned in a generic way about building “richer” applications in the browser and Javascript’s role in building those applications. Additionally, I was interested in the possibility of using Javascript on the server, and was starting to learn about Node.js.

A year later, I have some more refined ideas. The fragmentation of mobile platforms means that open web technologies are the only way to deliver applications across the spectrum of telephones, tables, televisions and what have you, without incurring the pain of multi platform development. The types of applications that are most interesting to me are highly interactive with low latency user interfaces – note that I am intentionally avoiding the use of the word “native”. Demand for these applications is going to raise the bar on the skill sets of web developers. I think that we will see more applications where the bulk of the interface and logic are in the browser, and where the server becomes a REST API endpoint. The architecture of “New Twitter” is in this vein. API endpoints have far less of a need for HTML templating and server side MVC frameworks. But those low latency applications are going mean that servers are doing more asynchronous delivery of data, whether that is via existing Comet like techniques or via Websockets (once it finally stabilizes). Backend systems are going to partition into parts that do asynchronous delivery of data, and other parts which run highly computationally intensive jobs.

I’ll save the discussion of the server parts for my Nodeconf writeup, but now I’m ready to report on JSConf.

Talks

Here are some of the talks that I found interesting or entertaining.

Former OSAF colleague Adam Christian talked about Jellyfish, which is a tool for executing Javascript in a variety of environments from Node to desktop browsers to mobile browsers. One great application for Jellyfish is testing, and Jellyfish sprang out of the work that Adam and others did on Windmill.

It’s been a while since I looked at Bespin/Skywriter/Ace, and I was pleased to see that it seems to be progressing quite nicely. I particularly liked the Github support.

I enjoyed Mary Rose Cook’s account of how writing a 2D platform game using Javascript cause her to have a falling in love like experience with programming. It’s nice to be reminded of the sheer fun and art of making something using code.

Unfortunately I missed Andrew Dupont’s talk on extending built-ins. The talk was widely acclaimed on Twitter, and fortunately the slides are available. More on this (perhaps) once I get some time to read the slide deck.

Mark Headd showed some cool telephony apps built using Node.js including simple control of a web browser via cell phone voice commands or text messages. The code that he used is available, and uses Asterisk, Tropos, Couchbase, and a few other pieces of technology.

Dethe Elze showed of Waterbear, which is a Scratch-like environment running in the browser. It’s not solely targeted at Javascript, which I have mixed feelings about. My girls have done a bunch of Scratch programming, so I am glad to see that environment coming to languages that are more widely used.

The big topics

There were four talks in the areas that am really concerned about, and I missed one of them, which was Rebecca Murphey’s talk on Modern Javascript, which appeared to be derived from some blog posts that she has written on the topic. I think that the problems she is pointing out – ability to modularize, dependency management, and intentional interoperability are going to be major impediments to building large applications in the browser, never mind on the server.

Dave Herman from Mozilla did a presentation on a module system for the next version of Javascript (which people refer to as JS.next). The design looks reasonable to me, and you can actually play with it in Narcissus, Mozilla’s meta circular Javascript interpreter, which is a testbed for JS.next ideas. One thing that’s possible with the design is to run different module environments in the same page, which Dave demonstrated by running Javascript, Coffeescript, and Scheme syntaxed code in different parts of a page.

The last two talks of the conference were also focused on the topic of JS.next.

Jeremy Askenas was scheduled to talk about Coffeescript, but he asked Brendan Eich to join him and talk about some of the new features that have been approved or proposed for JS.next. Many of these ideas look similar to ideas that are in Coffeescript. Jeremy then went on to try and explain what he’s trying to do in Coffeescript, and encouraged people to experiment with their own language extensions. He and Brendan are calling programs like the Coffeescript compiler, “transpilers” – compilers which compile into Javascript. I’ve written some Coffeescript code just to get a feel for it, and parts of the experience reminded me of the days when C++ programs went through CFront, which then translated them into C which was then compiled. I didn’t care for that experience then, and I didn’t care for it this time, although the fact that most of what Coffeescript does is pure syntax means that the generated code is easy to associate back to the original Coffeescript. There appears to be considerable angst around Coffeescript, at least in the Javascript community. Summarizing that angst and my own experience with Coffeescript is enough for a separate post. Instead I’ll just say that I like many of the language ideas in Coffeescript, but I’d prefer not to see Coffeescript code in libraries used by the general Javascript community. If individuals or organizations choose to adopt Coffeescript, that’s fine by me, but having Coffeescript go into the wild in library code means that pressure will build to adapt Javascript libraries to be Coffeescript friendly, which will be detrimental to efforts to move to JS.next.

The last talk was given by Alex Russell, and included a triple head fake where Alex was ostensibly to talk about feature detection, although only after a too long comedic delay involving Dojo project lead Pete Higgins. A few minutes into the content on feature detection, Alex “threw up his hands”, and pulled out the real topic of his talk, which is the work that he’s been doing on Traceur, which is Google’s transpiler for experimenting with JS.next features. Alex then left the stage and a member of the Traceur team gave the rest of the talk. I am all in favor of cleverness to make a talk interesting, but I would have to say that the triple head fake didn’t add anything to the presentation. Instead, it dissipated the energy from the Brendan / Jeremy talk, and used up time that could have been used to better motivate the technical details that were shown. The Traceur talk ended up being less energetic and less focused than the talk before it, which is a shame because the content was important. While improving the syntax of JS.next is important, it’s even more important to fix the problems that prevent large scale code reuse and interoperability. The examples being given in the Traceur talk were those kinds of examples, but they were buried by a lack of energy, and the display of the inner workings of the transpiler.

I am glad to see that the people working on JS.next are trying to implement their ideas to the point where they could be used in large Javascript programs. I would much rather that the ECMAScript committee had actual implementation reports to base their decisions on, rather than designing features on paper in a committee (update: I am not meaning to imply that TC39 is designing by committee — see the comment thread for more on that. ). It is going to be several more years before any of these features get standardized, so in the meantime we’ll be working with the Javascript that we have, or in some lucky cases, with the recently approved ECMAScript 5.

Final Thoughts

If your interests are different than mine, here is a list of pointers to all the slides (I hope someone will help these links make it onto the Lanyrd coverage page for JSConf 2011.

JSConf is very well organized, there are lots of social events, and there are lots of nice touches. I did feel that last year’s program was stronger than this years. There are lots of reasons for why this might be the case, including what happened in Javascript in 2010/11, who was able to submit a talk, a change in my focus and interests. Chris Williams has a very well reasoned description of how he selects speakers for JSConf. In general I really agree with what he’s trying to do. One thing that might help is to keep all the sessions to 30 minutes, which would allow more speakers, and also reduce the loss if a talk doesn’t live up to expectations.

On the whole, I definitely got a lot out the conference, and as far as I can tell if you want to know what is happening or about to happen in the Javascript world, JSConf is the place to be.

Ecma TC39 is *not* doing “design by committee”. We are codifying (with cleanups) _de facto_ standards where we can. Where the language needs new semantics, e.g. modules, the designers are individuals and pairs of TC39 members.

More important: browser vendors prototype the draft standards that reach “Harmony” status and are slated for inclusion in ES.next, so you will not have to wait three years to use these features.

This is how HTML5 and many modern CSS and Web API (DOM) features rolled out — as draft standards with coopetition-driven implementations among the agile browsers.

Yes, IE was slow to catch up. We’ll see how that plays out with rolling IE10 preview releases and Microsoft’s diminished browser market power.

Between transpilers and rolling prototype-to-final implementations, JS changes should come out quickly. Not as fast as Python evolution on the best days, but comparable.

The debugging hardships of cfront (I remember it too well) and similar translated languages are being addressed. CoffeeScript is “just syntax” so it lines up line numbers where it can.

And more important, we at Mozilla are working on primary-source line and column number mappings for debuggers. I think the V8 folks are interested too.

CoffeScript libraries are unlikely in the wild, but Rails 3 bundles CoffeeScript and makes building super-convenient, and IINM also makes view-(primary-)source work (fetching the .coffee file instead of showing you the compiled .js).